| 摘要 |
Saddle warpage of a wiring board at the time of reflow soldering is reduced by canceling out a difference in thermal expansion amount between wiring layers with anisotropy due to variations between the wiring layers in the proportion of copper remaining in the wiring layers C and non-uniformity of wiring elements by a difference in thermal expansion amount with anisotropy between resin base material layers produced according to the material of fiber bundles forming a warp or a weft in at least one resin base layer B, different from the material of other fiber bundles.
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